Torque control impact wrench locking system

ABSTRACT

A lock mechanism for an impact wrench containing a torsion bar torque control system including a torsion bar, an annular member surrounding the torsion bar, a sleeve slideably splined on the annular member, a nut threaded on the annular member for adjusting the sleeve along the member, and a gear key for adjusting the nut and engaging gear teeth on the nut and a radial hole on the sleeve. The locking means includes a series of detent recesses on the sleeve and a spring-pressed detent contained in the nut for selectively engaging the recesses to prevent the nut from turning when the gear key is withdrawn from the mechanism. A ring is slideably mounted on the sleeve and located to force the detent to a nonlocking position when the gear key is inserted in its radial hole contained in the sleeve.

United States Patent [72) inventor Ylk Y. Young Elmira, NY. [2|] Applv No. 12,274 [22] Filed Feb. I8, 1970 [45] Patented July 13, 1971 [73} Assignee lngemll-Rand Company New York, N.Y.

[S4] TORQUE CONTROL IMPACT WRENCH LOCKING SYSTEM 2 Chis, 4 Drawing Figs.

[52] U.S. CI 173/916, 64/15 R, 64/27 [51] lnt.Cl B25b 23/14 [50] FleldotSear-eh 173/12, 93.5, 93.6; 64/] 5, 27

[56] References Cited UNITED STATES PATENTS 2,822,677 2/1958 173/916 X 2,923.l9l 2/l960 Fulop ABSTRACT: A lock mechanism for an impact wrench containing a torsion bar torque control system including a torsion bar, an annular member surrounding the torsion bar, a sleeve slideably splined on the annular member, a nut threaded on the annular member for adjusting the sleeve along the member, and a gear key for adjusting the nut and engaging gear teeth on the nut and a radial hole on the sleeve. The locking means includes a series of detent recesses on the sleeve and a spring-pressed detent contained in the nut for selectively engaging the recesses to prevent the nut from tuming when the gear key is withdrawn from the mechanism. A ring is slideably mounted on the sleeve and located to force the detent to a nonlocking position when the gear key is inserted in its radial hole contained in the sleeve.

53 Z 5 L- E 5 3 'i 4 57 PATENTED JUL 1 3 IHTI INVENTOR Y//\ Y. YOUNG EM 0.?W

ATTORNFY TORQUE CONTROL IMPACT WRENCH LOCKING SYSTEM BACKGROUND OF INVENTION This invention relates to rotary impact wrenches having a torsion bar torque control means for controlling and limiting the magnitude or value of torque applied by the wrench to a fastener, such as a nut or the like.

A conventional rotary impact wrench having an adjustable torque limiting means is disclosed in the US. Pat. No. 2,822,677 issued Feb. ll, l958 to H. C. Reynolds. This tool includes an axially extending torsion bar spring which is utilized to transmit rotary impacts to a fastener. The torsion bar is wound or prestressed to a predetermined value of torque corresponding to the maximum torque load that is to be transmitted by the torsion bar to the fastener. By being prestressed, the torsion bar transmits torque loads as a rigid nondeflecting coupling so long as the transmitted torque is equal to or less than the prestressed torque on the torsion bar by the rotary impact tool exceeds the prestressed torque of the torsion bar, the torsion bar begins acting as a spring, instead of a rigid coupling, and deflects an additional amount and then rebounds to absorb and dissipate the excessive impact torque load without transmitting it to the fastener. The torsion bar is commonly known as a "prestressed or preloaded torsion bar.

SUMMARY OF INVENTION The principal object of this invention is to provide a novel locking mechanism for preventing the adjusting mechanism of a torsion bar torque control system of an impact wrench from moving out of adjustment during operation.

Another important object of this invention is to provide a novel locking system for an impact wrench torsion bar control system which automatically releases when an adjusting tool is applied to the torque control system.

In general, the foregoing objects are attained in an impact wrench containing a preloaded or prestressed torsion bar in terconnecting the impact mechanism to the spindle. An annular member surrounds the torsion bar and a sleeve slideably mounted on the annular member is adjusted along it to vary the prestressed load on the torsion bar. A nut is threaded on the annular member to force the sleeve axially to adjust the prestressed load. A gear key system is used for adjusting the nut and includes a gear key, a series of gear teeth located on the nut, and a radial hole provided in the sleeve to receive the key. A locking system is provided to prevent the nut from turning when the key is withdrawn from the sleeve and in cludes a series of detent recesses provided on the end of the sleeve, and a spring-pressed detent contained in the nut for engaging one of the recesses. A ring is slideably mounted on the sleeve and is arranged to disengage the detent from the recess when moved axially. The ring is arranged to partially cover the radial hole in the sleeve when the key is withdrawn so that the ring must be moved axially to disengage the detent when the key is inserted into the sleeve hole.

BRIEF DESCRIPTION OF DRAWING The invention is disclosed in the accompanying drawings wherein:

FIG. I is a fragmentary elevational view with parts cut away and shown in section of an impact wrench utilizing one embodiment ofthe invention;

FIG. 2 is an enlarged fragmentary view with parts shown in section of the front spindle portion of the wrench in FIG. I; and I FIGS. 3 and 4 are respective sections taken on lines 3-3, and 4-4 in FIG. 2.

2 DESCRIPTION OF PREFERRED EMBODIMENT The impact tool or wrench I shown in FIGS. 1 to 4 includes a casing 2 having a front nose 3, a pistol-shaped handle portion 4, and a rear cap 5. The handle 4 carries a trigger 6 which is connected to a throttle valve (not shown) and is operative to feed fluid pressure to the wrench motor (not shown). The motor drives a conventional rotary impact mechanism 9 including a hammer l0 and an anvil II. The impact mechanism 9 delivers rotary impacts to a spindle 12 in a manner which is well known in the impact wrench art. All of the foregoing structure is conventional and, for that reason, is not described in detail.

The anvil 11 includes an integral forwardly extending tubular portion [5 journaled in a bearing 16 mounted in the nose 3 of the impact tool casing 2. The tubular portion 15 ofthe anvil surrounds an elongated torsion spring or bar 17 having its rear end I8 formed as a square plug nonrotatably anchored in a corresponding square hole in the anvil I] so that impacts received by the anvil I] from the hammer II) are rigidly coupled to the upper end of the torsion bar 17. The forward end of the torsion bar I7 is integrally connected to the spindle 12 which is adapted to engage a socket (not shown) having a square hole for detachably receiving the square forward drive end ofthe spindle I2.

The impact energy received by the anvil ll is transmitted by the torsion bar 17 to a workpiece. In order for the torsion bar 17 to accomplish this, it must be wound or prestressed under a torque which is equal to or greater than the torque of the impacts being transmitted. Once the torsion bar 17 is wound under a given torque load, it acts as a rigid coupling in transmitting torque loads which are equal to or less than the prestressing torque of the torsion bar. In other words, so long as the torque loads applied to the torsion bar 17 do not exceed its prestressed torque, no further deflection of the torsion bar occurs.

When the impact load applied to the torsion bar 17 exceeds its prestressing torque, the bar deflects or winds up additionally under each impact and then rebounds, resulting in the impact being absorbed substantially by the torsion bar without transmitting it to the workpiece. Thus, the torsion bar 17 acts to limit the maximum torque applicable to a workpiece to a value of torque equaling substantially the prestressed torque of the bar 17.

A tube 25 containing a pair of diametrically located slots 26 in its forward end is located on the torsion bar 17 with the slots 26 received over and keyed on wings 2i mounted on the front end of the torsion bar I7. The main portion of the tube 25 extends rearwardly from the wings 21 and has a rear end 27journaled in the forward end of the tubular portion 15 of the anvil I1. The exterior of the tubular portion 15 contains a series of helically arranged splines 29 and the exterior of the tube 25 contains a series of longitudinally extending splines 30 which are also provided with a thread 31. A sleeve 33 is mounted over both the tube 25 and the tubular portion 15 and includes cooperating axial flutes on its forward end and helical flutes on its rear end to interconnect the tubular portion 15 with the tube 25. A nut 34 is threaded on the thread 3i of the tube 25 and engages the forward end of the sleeve 33 whereby it can be adjusted to wind up the torsion bar I7 thereby applying a preload torque to the bar 17. The sleeve 33 winds up the torsion bar I7 as it moves rearward on the helical splines 29, due to the helix of the splines 29. During operation of the wrench, when the torque load on the torsion bar I7 exceeds the prewourid torque, the torsion bar will be wound up further, resulting in the excessive torque being expended in the torsion bar in a known manner.

The nut 34 is provided at its rear face with a series of beveled gear teeth 53 adapted to engage the teeth 54 ofa conventional Jacob's chuck key 55 in the same manner that it is used on the conventional Jacob's drill chuck. During the use of the chuck key 55 the axle pin 56 seats in a radially opening hole provided in the sleeve 33 as shown in FIG. 2.

Means is provided for automatically locking the nut 34 in an adjusted position on the sleeve 33 when the chuck key 55 is withdrawn from the operative position shown in FIG 2, The nut 34 carries a tang 57 slidably mounted therein in a corresponding longitudinally extending slot and urged rearwardly by a spring 58, FIG. 4 shows three tangs 57 located at l2ll intervals. The forward edge of the sleeve 33 is provided with a series of forwardly opening notches 59 adapted to receive the tangs $7 to lock the nut 34 against turning relative to the sleeve 33v A ring 51 surrounds the sleeve 33 and seats against the front portion of the tangs 57 where it can be moved forwardly to force the tangs 57 forward out of notches 59. The ring 51 is wide enough to partially cover the hole in the sleeve 33 when the chuck key 55 is removed so that it must be moved forward to insert the axle pin 56 into its hole. in moving forward, the ring 51 forces the tangs 57 out of the notches 59, thereby automatically unlocking the nut 34 so that it can be turned by the chuck key 55.

While only a single embodiment of the invention is shown and described in detail, this invention is not limited simply to the specifically described embodiment, but contemplates other embodiments and variations which utilize the concepts and teachings of this invention.

lclaim:

I. A locking system for an impact wrench containing a tor sion bar torque control system, comprising:

a torsion bar torque control mechanism including a torsion bar, an annular member surrounding the torsion bar and fixed to one ofits ends, a sleeve slidably and nonrotatably mounted on said annular member for sliding along said member to adjust the prestressed torque load on the torsion bar and a nut threaded on said member to drive said sleeve along said member for adjustment purposes;

the end of said sleeve adjacent said nut containing a plurality of detent recesses;

a spring-pressed detent mounted in said nut to engage one of said recesses to prevent said nut from being turned; and

a ring mounted on said sleeve and adapted to disengage said detent when forced axially toward said nut.

2. The system of claim 1 including:

a key mechanism for adjusting said nut including gear teeth on said nut, a gear key, and a hole in said sleeve adapted to receive said key when adjusting said nut; and

said ring being located to partially cover said hole whereby said ring must move axially on said sleeve to disengage said detent in order for said key to be inserted into said hole. 

1. A locking system for an impact wrench containing a torsion bar torque control system, comprising: a torsion bar torque control mechanism including a torsion bar, an annular member surrounding the torsion bar and fixed to one of its ends, a sleeve slidably and nonrotatably mounted on said annular member for sliding along said member to adjust the prestressed torque load on the torsion bar and a nut threaded on said member to drive said sleeve along said member for adjustment purposes; the end of said sleeve adjacent said nut containing a plurality of detent recesses; a spring-pressed detent mounted in said nut to engage one of said recesses to prevent said nut from being turned; and a ring mounted on said sleeve and adapted to disengage said detent when forced axially toward said nut.
 2. The system of claim 1 including: a key mechanism for adjusting said nut including gear teeth on said nut, a gear key, and a hole in said sleeve adapted to receive said key when adjusting said nut; and said ring being located to partially cover said hole whereby said ring must move axially on said sleeve to disengage said detent in order for said key to be inserted into said hole. 